In the art of cooking foods, it is common practice to "deep fry" certain foods by immersing those foods in large volumes of heated fats or oils. Further, in many instances, foods that are deep fried are first dipped in a suitable flour base batter which browns and establishes an attractive and tasty crust on and about the foods during deep frying of the foods.
In the commercial food industry, deep frying of foods is carried out in deep fryers which consist of large upwardly opening vessels in which large volumes of cooking oil are deposited and which include thermostatically controlled gas or electric heating elements to heat and maintain the oils in the vessels at desired cooking temperatures. Generally, the cooking temperatures in deep fryers range from 325.degree. F. to 400.degree. F.
The oil used in deep fryers is costly and is subject to being rapidly degraded and rendered unsuitable for use by the burning and heat reduction of the food stuff cooked therein. While certain fatty acids leeched and/or rendered from foods during deep frying adversely react with and degrade cooking oils, the most common and notable adverse effects and degrading of such oils is caused by bits and pieces of food which separate from the food being cooked and which remain suspended in the cooking oil to eventually burn or become reduced to varnish like sludge. The burned food stuff and/or residue in cooking oils in deep fryers discolors the oils and the foods cooked therein; impart a burned or otherwise unpleasant taste and odor to the foods cooked therein and oftentimes clings to and contaminates the foods cooked therein, rendering them unattractive and unsuitable to be served and eaten.
As a result of the above, to extend the useful life of cooking oils in deep fryers, the prior art has provided numerous different forms of oil filtering machines expressly made to remove those materials and/or impurities which, if left in the oils, will result in the rapid and premature degradation thereof.
The majority of the prior art filtering machines for the purpose set forth above, of which I am familiar, are rather simple in form and are generally characterized by large holding tanks, which tanks are sufficiently large to receive and hold the full supplies of oil in the cooking vessels of the deep fryers that the machines are intended to service. Such machines are further characterized by liquid handling systems including motor driven pumps and valves which operate to draw oil from deep fryers and deliver it into the holding tanks of the machines and to thereafter move the oil from the holding tanks back into the deep fryers. Finally, such machines are characterized by special and unique filtering devices to filter the oils handled thereby, as the oils are moved from the deep fryers into the holding tanks of the machines.
One major shortcoming common in most prior art oil filtering machines of the character here concerned is that their holding tanks are necessarily quite large and the resulting machines are so large and space-consuming that they are difficult and troublesome to use in those confined quarters or areas in which deep fryers are commonly used.
Another major shortcoming in most prior art oil filtering machines resides in the fact that they operate to receive the full supplies of oil in the deep fryers which they service and require that the deep fryers be put out of service when their supplies of oil are being filtered. Thus, filtering of the oil in deep fryers by those machines provided by the prior art must, as a general rule, be put off or postponed to those periods of time when the deep fryers are not otherwise in use.
Another major shortcoming in most prior art oil filter machines resides in the fact that the hot oils drawn from the deep fryers being serviced are let to cool during filtering thereof and are returned to the deep fryers cold or at a much reduced temperature. As a result of the foregoing, the oils must be reheated in the deep fryers before deep frying can be resumed. Such reheating of the oils in deep fryers is an undesirable, costly time and power-consuming operation.
To the best of my knowledge and belief, the prior art in recent years has directed much attention to the development and provision of unique and highly sophisticated oil filtering means which operate or are intended to operate to remove, neutralize or otherwise counteract the adverse effects of those fatty acids and the like which are leached or rendered from foods being cooked and which will ultimately result in degrading cooking oil to an extent that it can no longer be used. While the removal, neutralizing or otherwise counteracting the adverse effect of fatty acids and the like in cooking oil will extend the useful life of such oils and might be a desirable practice in some instances, it appears clear that it is seldom a practical and cost-effective practice. In most instances, when the oil in deep fryers has been used so long and has been so contaminated with fatty acids and the like that it is no longer fit for use, it is most cost-effective and practical to dispose of it and replace it with a fresh supply of oil.
In accordance with the above, for the most practical and cost-effective use of oils in deep fryers, it is only necessary that those solids which if left to remain in the oils, will burn and adversely affect the color, taste and odor of the oils, be removed therefrom before their adverse effects are attained.